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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 3 |
| 3 | 15 |
| 4 | 42 |
| 5 | 602 |
| 6 | 2440 |
| 7 | 61915 |
| 8 | 322776 |
| 9 | 12297978 |
| 10 | 77360796 |
| 11 | 4044784633 |
| 12 | 29562890886 |
| 13 | 2004648242718 |
| 14 | 16604827619828 |
| 15 | 1404640885455993 |
| 16 | 12954736337254696 |
| 17 | 1328741141974378250 |
| 18 | 13465808369740333664 |
[2,3,15,42,602,2440,61915,322776,12297978, 77360796,4044784633,29562890886,2004648242718, 16604827619828,1404640885455993,12954736337254696, 1328741141974378250,13465808369740333664] |